A string representing a numeric value (Java implementation)

Implement a function to determine whether a string represents a numeric value (including integers and decimals). For example, the string "+100", "5e2", "123", "3.1416" and " -1E-16" all represent numeric values. But "12e", "1a3.14", "1.2.3", "+-5" and "12e+4.3" are not.

1  Public classDemo2 {2 3     //array subscript member variable4     intindex; 5   6      Public BooleanIsnumeric_2 (Char[] str) {  7         //Input Exception8         if(str = =NULL)  9             return false; Tenindex = 0;  One         //start with a positive sign A         if(Str[index] = = ' + ' | | str[index] = = '-')   -index++;  -         if(Index = =str.length) the             return false;  -         //set numeric to determine whether a number -         Booleannumeric =true;  - scandigits (str);  +         if(Index! =str.length) { -             //decimal +             if(Str[index] = = '. ') {   Aindex++;  at scandigits (str);  -                 if(Index < Str.length && (str[index] = = ' E ' | | str[index] = = ' E '))   -numeric =isexponential (str);  -}Else if(Str[index] = = ' E ' | | str[index] = = ' E ')   -numeric =isexponential (str);  -             Else   in                 //An exception character has occurred -numeric =false;  to         }   +    -         returnNumeric && Index = =str.length;  the     }   *    $     //Scan an array, if the current character is a number, index++Panax Notoginseng     Private voidScandigits (Char[] str) {   -          while(Index < str.length && Str[index] >= ' 0 ' && Str[index] <= ' 9 ')   theindex++;  +     }   A    the     //determines whether the end of a numeric value represented by scientific notation +     Private BooleanIsexponential (Char[] str) {   -         if(Str[index]! = ' E ' && str[index]! = ' E ')   $             return false;  $index++;  -         if(Index = =str.length) -             return false;  the         if(Str[index] = = ' + ' | | str[index] = = '-')   -index++; Wuyi         if(Index = =str.length) the             return false;  - scandigits (str);  Wu         //If there are special characters, index will not be str.length -         returnindex = = str.length?true:false;  About     }   $}

Reprinted from: http://blog.csdn.net/zjkc050818/article/details/72818475

A string representing a numeric value (Java implementation)